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Liu F.,Zhejiang Sci-Tech University | Wu C.,Zhejiang Sci-Tech University | Wu C.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Sun L.,Zhejiang Sci-Tech University | Sun L.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

Generally, revolute joints are considered to be ideal in dynamic analysis of crank-rocker type transplanting mechanism. However, in reality, clearances in revolute joints are unavoidable due to uncertainties such as manufacturing tolerances, assembly errors and wear. When a revolute joint clearance is introduced, the relative position of the axle pin and axle cover is uncertain, which will affect the dynamic responses of the transplanting mechanism. In order to investigate the influence of the revolute joint clearance on the crank-rocker type transplanting mechanism, the dynamic model of the crank-rocker type transplanting mechanism with a revolute joint clearance was established based on the dynamics theory and the Lankarani-Nikravesh contact force model. The revolute joint clearance will introduce 2 extra degrees of freedom, and a stable solution cannot be obtained by solving the dynamic directly, so the dynamic model was solved by the four-order Runge- Kutta method. The parameters of the simulation calculation were obtained according to the actual parameters of transplanting mechanism and literatures. The influence of revolute joint clearance on trajectory, velocity, acceleration and taking seedling position of the needles to take seedlings was analyzed by Matlab. The results showed that the revolute joint clearance had little influence on trajectory, velocity and taking seedling position of the needles to take seedlings, and the revolute joint clearance had great influence on acceleration of the needles to take seedlings; with the increase of revolute joint clearance, the deviation of taking seedling position of transplanting mechanism would be greater, and the amplitude and fluctuation range of acceleration of the needles to take seedlings would increase. In order to quantitatively describe the influence of various revolute joint positions with clearance on acceleration of the needles to take seedlings, the average acceleration was used as the evaluation criterion of the influence. In addition to the revolute joint connected to the drive, the average accelerations of 3 various revolute joints with various clearances were obtained by simulation analysis. For the 3 revolute joint clearances, the revolute joint clearance between the crank and the connecting rod had the greatest influence on acceleration of the needles to take seedlings according to the comparison result of the average accelerations. The continuous contact model was also used to analyze the influence of the revolute joint clearance on acceleration. In order to verify the correctness of the simulation analysis and to select the simulation model whose calculation results were more in line with the actual ones, a test bench was established. An accelerometer and a data acquisition and analysis system were used to measure acceleration of the needles to take seedlings. In the test, the rolling bearing was regarded as ideal revolute joint, and the fit between sliding bearing and shaft with different radii was regarded as the revolute joint with clearance. The average acceleration of the test was larger than that of the simulation under the same condition due to some factors such as manufacturing tolerances, clearance of the rolling bearing and vibration. The conclusion that the revolute joint clearance between the crank and the connecting rod has the greatest influence on acceleration can be also obtained according to the test. By comparing the test and simulation results, the Lankarani-Nikravesh contact force model is more suitable for the analysis of the mechanism with revolute joint clearance than the continuous contact model. The relative errors of average acceleration between simulation based on the Lankarani-Nikravesh contact force model and test were within 3.6% under revolute joint C or D with clearance. The relative errors of average acceleration were within 8.1% under revolute joint B with clearance. The same conclusions can be obtained with the average accelerations of simulation and the average accelerations of test. So the correctness of simulation analysis based on the Lankarani-Nikravesh contact force model was verified by the test results. This research provides the reference for structural optimization design and accuracy allocation of crank-rocker type transplanting mechanism. © 2016, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.


Zhao X.,Zhejiang Sci-Tech University | Zhao X.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Wang C.,Zhejiang Sci-Tech University | Yang M.,Zhejiang Sci-Tech University | And 4 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

Seedling pick-up mechanism is the core mechanism of dry land automatic transplanting machine, and it replaces the traditional manual labor, which picks up seedlings from seedling box folder and sends the single seedling to the planting machine. The dry land automatic transplanting machines in Japan, South Korea and other countries adopt to bar and slider mechanism scheme or adopt chute in combination mechanism scheme, but they lack efficiency. China scholars do a lot of researches on making use of non-circular planetary gear train to achieve special non-circular trajectory, and this kind of transmission is a potential type of effective seedling pick-up mechanism, but it's very difficult to design non-circular planetary gear train mechanism when it is oriented to complex trajectory and needs to meet the attitude requirements, and the corresponding research is still not sufficient. Reverse solution is an effective way when oriented to mechanism design of complex work requirements, and the reverse design on how to plan the expected trajectory to meet the work requirements as well as the transmission ratio requirements, is the difficult points. Authors have conducted reverse design research on plug seedlings picking-up mechanism and proposed reproduced trajectory judgment criterion based on the monotonic mechanism of output member's relative angle. As to the expected trajectory, the applicability of the non-circular planetary gear system transmission can be judged by the monotonicity of relative angle curve. In this paper, the setting method of the key point in planning the expected trajectory is researched so as to facilitate the design of transmission ratio of non-circular gear, and the determination process of data point is given, which satisfies the requirement of working trajectory and attitude; through compiling mechanism's design software, a set of mechanism parameters are determined, and the simulation is carried out by ADAMS and the result is compared with that of the original design. The results achieved by this article are: the minimum distance between trace and seedling transport box is 21 mm, the minimum width of beak dimension is 2.07 mm, the inclined angle of beak shape is 136.4°, the winging angle of picking-up seedling arm is 24.3° in the feeding periods and is 3.6° in the periods of leaving seedling box, the angle of pushing seedling is 76°, the module of gear is 2.53 mm, height of trace is 285 mm, and the maximum transmission ratio of non-circular gears is 1.81. There are some improvements in the results of new design: the minimum width decreases by 3.88 mm in the seedling period; the winging angle of picking-up seedling arm decreases by 2.43° in the feeding period, which is thus useful to picking-up seedling and transplanting seedling; the distance between the trajectory and the delivering plate increases by 8.75 mm in the return period, which improves safety margin between taking seedling mechanism and delivering device; the highest point of trajectory drops by 42.67 mm, the lowest point of trajectory drops by 3.89 mm, the largest angle of picking-up arm drops from 62.21° to 55.47°, and the maximum transmission ratio of non-circular gears decreases from 1.92 to 1.81. The research in article provides a better choice for the picking-up seedling mechanism, and the reproduced trajectory judgment criterion and the trajectory planning method can give a reference for the design of non-circular gear planetary system. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.


Yu G.,Zhejiang Sci-Tech University | Yu G.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Du L.,Zhejiang Sci-Tech University | Du L.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | And 7 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

With the aim to realize feeding seedlings stably, accurately and quickly, this paper introduces a feeding-seedling device for the high-speed feeding-seedling device for pot-seedling. This device reduces the moving distance of the seedling box when operating by using a periodic non-uniform lateral shift box. And with the proposed seedling vertical driving device, vertical seedling gains its accuracy and stability as well as high speed. The operational principle of the lateral feeding-seedling device was firstly elaborated, followed by its structure design. Secondly, working principle of the seedling vertical driving device was analyzed and its kinematics model was established. Then a set of feasible parameters was obtained by Matlab and applied in the following device design. Finally, a validation test was carried out. The test result indicates that the seedling box of the proposed lateral feeding-seedling device gains shorter distance when picking seedlings, with a 37% reduction from the traditional one. Moreover, this device achieves error within ±2 mm in single feeding and without cumulative error. The proposed feeding-seedling device is able to support pot-seedling speed of 200~250 times/min. ©, 2015, Chinese Society of Agricultural Machinery. All right reserved.


Du L.,Zhejiang Sci-Tech University | Du L.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Yu G.,Zhejiang Sci-Tech University | Yu G.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | And 6 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

As one of special rice seedling, the pot-blanket seedling is a method between the rice pot seedling and blanket seedling. Because of its low damage to seedling and root while transplanting, fast reviving, and earlier rooting and tillering after transplanting, the mechanical planting of pot-blanket seedling is enabled to be high yield and more efficient. Compared with the ordinary seedling, its yield can increase 5%-15%. In China, rice is the principal food, so it is very significant to research the planting technology of pot-blanket seedling. However, there is no existing transplanter specially for pot-blanket seedlings. Vertical feeding-seedling device of existing high-speed transplanter being used has following problems: 1) With the influence of gravity and vibration, seedlings will slide down on flat belt, when vertical feeding-seedling device does not work and cannot be fixed. 2) One-way bearing can also be rotated unidirectionally with the force of vibration so that seedling cannot be fed accurately. 3) The accumulative transmission error of one-way bearing will increase with time. As a result, the vertical feeding seedling cannot be quantified accurately. In order to solve the problem that vertical feeding seedling is impossible to be quantified accurately with use of high-speed transplanter, in the paper, a new kind of rice pot-blanket feeding-seedling device was designed and improved for rice pot-blanket seedlings. After analyzing and summarizing the planting traits of rice pot-blanket seedling on references at home and abroad, a device with intermittent rod mechanisms, four-bar mechanism, a double-ratchet mechanism which applies to platform of high-speed transplanter was analyzed theoretically and structured to satisfy the requirements of rice pot-blanket seedlings. By used of Solid Works, it will be enabled to test its work conditions in virtual simulation. And a prototype was successfully developed. The experiment showed that the deviation of one-pass vertical feeding quantity was less than 2 mm and there was no accumulative error after repeated feeding. In the condition of high-speed operation, vertical feeding seedling was accurate and stable. The position of seedlings can be fixed when the device under inactive condition. The research can provide a reference for design and application of rice transplanters.


Zhao X.,Zhejiang Sci-Tech University | Zhao X.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Shen M.,Zhejiang Sci-Tech University | Shen M.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

Picking seeding tache in plug seedings of cotton transplanting is completed manually at present. As a result, the efficiency of cotton transplanting is limited. In order to realize automatic pick-up in seedlings in cotton transplanting, a new kind of seedling pick-up mechanism was designed which adapts with the characteristics of the stems' matrix tensile force of the cotton seedlings in nursery medium which is much larger than the fetching seedling force. A new form of planetary gearing system that is composed with blended high-order deformed elliptic gears was introduced. Mechanism kinematics mathematical model was established, the objective of clipping seedling type working with seeding pick-up mechanism were set according to the demand of the clipping seedling type. Working and the demand of coordination between the seeding pick-up mechanism and seeding box, seeding transplanting mechanism, and optimize analysis of software were compiled to determine the parameters of institutions: the center distance of the meshing gear is 58 mm, the eccentricity ratio of first stage second order deformation elliptical gear is 0.2, the major deformation coefficient of first stage second order deformation elliptical gear is 0.9, the eccentricity ratio of second stage single deformation elliptical gear is 0.14, and the major deformation coefficient of second stage single deformation elliptical gear is 0.18. The installation angle of the mark line on the fixed sun gear 1 is 13π/18, the angle of planetary carrier OA and the mark line on the sun gear 1 is π/2, the first middle gear and the second middle gear are installed on the middle shaft A, the first middle gear that the meshing with sun gear, the angle of mark lines on the second middle gear and the first middle gear is 7π/18. At the initial position, the angle of the planetary carrier AB and the mark line of the second middle gear is 35π/36, the first planetary gear that the meshing with the second middle gear, the first planetary gear and the picking-up seedling claw are installed on the planetary shaft B, the angle of picking-up seedling claw BE and the mark line of the first planetary gear is π/6, the angle of BT to BE which on the picking-up seedling claw is 7π/18 and the BT length is 150 mm, the angle between the fetching seedling section of the trajectory to the seedlings box is 91°, the rotational angle of the planetary carrier is 36° and no interference between the seedling and the potting during the process of fetching seedlings, picking-up the seedling claw swing angle is 5°, and the angle between the fetching seedling section to the claw approach seedlings section is 85°, pushing the seedlings angle is 76°, the minimum distance between two pick-up seedling claws is 48.6 mm. The virtual experiment indicated that the mechanism's work trajectory is in agreement with theoretical calculations, well meets the demand of the seedling fetching process, the seedlings claws have a rapid fetching speed in fetching the seedling section which is beneficial to rapid fetching seedlings, cycle speed curve smoothing, and provides a viable solution for automatic fetching of cotton seedling in nursery medium.


Gao Q.,Zhejiang Sci-Tech University | Gao Q.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Du X.,Zhejiang Sci-Tech University | Du X.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | And 6 more authors.
American Society of Agricultural and Biological Engineers Annual International Meeting 2015 | Year: 2015

Vibratory harvesting technology has been widely discussed and intensively investigated in recent years. However, current research mostly focused on the effect of harmonic shaking with fixed joint between actuator and tree which could easily damage the tree body. To explore a more effective vibratory harvesting method, a vibratory harvester driven by gasoline engine with unequal stroke and without clamping the tree was proposed based on pushing and impacting dynamics. The harvester consisted mainly of the shaking mechanism, a steel cable, and the front actuator. The shaking mechanism had a crank-rocker mechanism and a crank-slider mechanism which was used to generate reciprocating motion with unequal stroke. And the steel cable was pulled and released under the running of the shaking mechanism. The front actuator driven by the steel cable had a spring-slider mechanism which was to generate a composite effect of pushing and impacting on branches of fruit tree when the branch was not fastened to the actuator. The kinematics of the shaking mechanism was analyzed and the working stroke equation was derived. A model of the harvester was established and simulated in ADAMS. The kinematics simulation shows that the stroke changed with the angle of the stroke-adjusting crank in the shaking mechanism. By combining ANSYS with ADAMS, a dwarf Chinese hickory tree was modeled as a flexible body and a rigid-flexible coupling model of the harvester and tree was established. The pushing-impacting interaction between the harvester and tree was simulated to obtain the displacement and acceleration of the pushing head in the front actuator and its impacting force upon the branch of the tree. Finally, based on the rigid-flexible coupling model, the influence of different stroke and clamping conditions on the tree dynamics response was analyzed by setting equal stroke or unequal stroke to the machine and by attaching the pushing head to the tree branch or without clamping. The result shows that the pushing-impacting harvester with unequal stroke has an effective excitation on the tree under the same shaking frequency. Copyright © (2015) by the American Society of Agricultural & Biological Engineers All rights reserved.


Tong J.,Zhejiang Sci-Tech University | Tong J.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Jiang H.,Zhejiang University | Wu C.,Zhejiang Sci-Tech University | And 4 more authors.
American Society of Agricultural and Biological Engineers Annual International Meeting 2015 | Year: 2015

Transplanting healthy seedlings from high density to low-density trays for further growth, and replacing bad or missing plants with healthy ones are important tasks for seedlings cultivation in plug tray in greenhouse. Developing automated seedling transplanter to take the place of labor to do these repetion and heavy tasks are meaningful. Research progresses which include four dimensions key technology of automated transplanter are presented in this paper. They are suitable seedling plug states for mechanical transplanting, end-effector design and testing, methods for seedling quality evaluation based on machine vision techniques, and seedling transplanting path optimization. Five parameters which include clamping needle angle, gripper needles, plug moisture content, taproot length, and bulk material proportion were tested separately to demonstrate the affection for plug compressive resistance. A plugging and clamping end-effector with two cylinder drivers was developed and tested with more than 958% success rate. Leaf area calculation methods were developed to evaluate seedling quality based on machine vision technology. Leaves overlapping problem was solved with more than 98.6% identification accuracy for vegetable seedling. Genetic algorithm was introduced into the transplanting path optimization. And the length has been shortened 8.5% and 3.7 m for transplanting fifty seedlings which compared with fixed sequential method. This knowledge is useful for developing automated seedling transplanter with effective end-effector, seedling detection, and transplanting strategy. Copyright © (2015) by the American Society of Agricultural & Biological Engineers.


He L.,Zhejiang Sci-Tech University | Wu C.,Zhejiang Sci-Tech University | Wu C.,Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province | Du X.,Zhejiang Sci-Tech University | And 5 more authors.
American Society of Agricultural and Biological Engineers Annual International Meeting 2015 | Year: 2015

Vibratory harvesting is an appropriate and efficient way to harvest the Chinese hickory fruits. To detach the fruits from trees, a shaker with large power was used to shake the trunk of fruit trees. However, there were some shortcomings of this way to harvest fruits, such as low efficiency and damages to trees. In this paper, in order to develop an efficient shaker for mechanical harvest, a new vibratory harvesting with multi-directional applied forced was studied. Firstly, the natural frequencies of tree were obtained under modal analysis by finite element software (ANSYS). Secondly, two harmonic forces with orthogonal- directions, the same amplitude and the same frequency were used to impact on the main branch of tree to determine the influence of tree's dynamic responses with respect to the force direction. Finally, a dynamic testing with vibratory was also implemented to find the relationship between the acceleration response and the mounted angle. Both from the simulation and testing, results show that the radial force may shake the loaded branch, while the axial force can drive the rest branches effectively. It illustrates that the multidirectional excitation is superior to a single-directional excitation for vibratory harvesting fruit.

Loading Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province collaborators
Loading Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province collaborators